#include <stdio.h>

void main()
{
    char letter;
    printf("Please input the first letter of someday.\n");
    while((letter=getch())!='Y')
    {
        switch(letter)
        {
            case 'S':printf("please input secong letter.\n");
                    if((letter=getch())=='a')
                    printf("saturday\n");
                    else if((letter=getch())=='u')
                    printf("sunday");
                    else printf("data error!\n");
                    break;
            case 'F':printf("friday\n");break;
            case 'M':printf("monday\n");break;
            case 'T':printf("please input second letter\n");
                    if((letter=getch())=='u')
                    printf("tuesday\n");
                    else if((letter=getch())=='h')
                    printf("thursday\n");
                    else printf("data error\n");
                    break;
            case 'W':printf("wednesday\n");break;
            default:printf("data error");
        }
    }
}